JPH064453A - Computer subsystem - Google Patents

Abstract

PURPOSE:To effectively execute an access by avoiding system-down against generation of a fault in a path for a device through a directory from a channel at the time when a CPU accesses a subsystem, with regard to the computer subsystem in which plural devices are connected through the directory to the channel of the CPU. CONSTITUTION:In each of devices 6-0-6-n, at least two ports alpha, beta are provided and the part between two device control parts 4-0, 4-1 is duplicated by a device interface 5. Also, in each of devices 6-0-6-n, a reserve release informing means 10 is provided, and when a forced reserve instruction is received from the another directory 4-1 and it is executed in a state that a reserve instruction received from one directory 4-0 is under execution, it is reported that a reserve state is released by the forced reserve instruction from the another directory to the directory 4-0 reserved before.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a computer subsystem in which a plurality of devices are connected to a CPU channel via a directory. In a subsystem in which an external storage device such as a magnetic disk device is connected to the computer main body, C
A PU connects to a path through a route that becomes a channel, a directory, or a device, but if the channel or directory fails during path connection or during reserve before path connection, the subsystem may go down. Therefore, it is desirable to be able to avoid a system failure due to such a down of some devices.

[0002]

2. Description of the Related Art As a conventional computer subsystem, for example, one shown in FIG. 9 is known. In FIG. 9, CP
U1 includes four channels (CH) 2-0 to 2-3,
Two directories (D
IR) 4-0, 4-1 to BMC interface (Block
Multiplex Channel Interface).

Within the subsystem are directories 4-0,
4-1 and, for example, five devices 6-0 to 6-n are SCS
It is connected by the I interface 5. In such a computer subsystem, for example, when the device 6-0 is reserved from the directory 4-0 and a forced reserve instruction from another directory 4-1 is received,
A forced reserve function is provided to release the reserve state from the directory 4-0 and bring the reserve state of the directory 4-1.

[0004]

However, in the computer subsystem having such a forced reserve function, the CPU 1 uses, for example, the channel 2-0, the directory 4-0 and the device 6-0 to execute the job. Depending on the failure factor, any one of them may go down when executing, and in this case, the following three failure problems are considered. [Case 1] When the channel 2-0 goes down while the channel 2-0, the directory 4-0 and the device 6-0 are in the path connection; the channel 2-0, the directory 4-0 and the device 6- are in the path connection. 0 remains connected. Since the system other than channel 2-0 is normal, CP
U1 attempts to access the subsystem using any of the other channels 2-1 to 2-3. However, since the directory 4-0 and the device 6-0 are still connected, the SCSI interface 5 is in a bus busy state, the CPU 1 cannot access the subsystem, and the subsystem goes down. [Case 2] When the directory 4-0 goes down while the channel 2-0, the directory 4-0 and the device 6-0 are in the path connection;
-0 can operate normally, so directory 4-0
Is detected and a reset instruction is given to the directory 4-0. However, since the directory 4-0 is down, even if the reset instruction is received, the connection between the directory 4-0 and the device 6-0 cannot be released, and the SCSI interface 5 remains in the bus busy state. Therefore CP
U1 cannot access the subsystem, and the subsystem goes down. [Case 3] When the channel 2-0 goes down after the device 6-0 is reserved through the directory 4-0 and before the path is connected; the path is not connected, the CPU 1 Can access the devices 6-1 to 4-1. However, since the device 6-0 is reserved for the channel 2-0, the device 6-0 can be accessed only by using the channel 2-0 and the directory 4-0. At this time, since the device 6-0 stores that it is reserved in the directory 4-0, it responds to the access from the directory-1 with device busy.

The CPU 1 detects that the channel 2-0 goes down, and uses the channel 2-1 to execute the device 6-.
Attempts to execute a forced reserve for 0. When the channel 2-1 can be used, the device 6-0 can be instructed to be reserved forcibly via the directory 4-0, and hence the channel 2-0 can be prohibited and the subsystem can be accessed thereafter.

If the channel 2-1 is being used by another I / O device, the CPU 1 uses the channel 2-2 or 2-3 to execute the forced reserve for the device 6-0 via the directory 4-1. To do. When the device 6-0 receives the forced reserve instruction, it releases the reserve of the directory 4-0 and enters the reserve state of the directory 4-1.
PU1 is device 6-0 via directory 4-1
Will be accessible.

However, the directory 4-0 is the device 6
Since it is not known that the reservation of −0 has been released, the device busy continues to be responded to the access from the channel 2-1 to the device 6-0, and the device from the channel 2-1 via the directory 4-0. You will not be able to access 6-0. If channel 2-0 is device 6-
When it goes down after instructing the reservation to all of 0 to 6-n, the directory 4-0 responds to the device busy to all accesses from the channel 2-1.
Despite the fact that the directory 4-0 is normal, the directory 4-0 actually appears to be down. Therefore, only the directory 4-1 can be used by the CPU 1 to access the subsystem, and the directory 4-0 can be used.
Throughput is reduced by the amount that can not be used.
The present invention has been made in view of such a conventional problem, and avoids a failure in the path from the channel to the device via the directory when the CPU accesses the subsystem. An object is to provide a computer subsystem that enables effective CPU access.

[0008]

FIG. 1 is a diagram for explaining the principle of the present invention. First, the present invention relates to a channel interface (B) for a plurality of channels 2-0 to 2-3 provided in the CPU 1.
At least two device control units 4-0 and 4-1 are connected via the MC interface 3 and a device interface (S) is connected to each of the device control units 4-0 and 4-1.
A plurality of devices 6 through CSI interface 5
The target is a computer subsystem in which 0 to 6-n are connected.

In the present invention for such a computer subsystem, at least two ports α and β are provided in each of the devices 6-0 to 6-n, and two device control units 4-0 and 4-1 are provided. Is individually connected to each of the ports α and β via the device interface 5. At the same time, one directory 4-0 is provided to each of the devices 6-0 to 6-n.
When the forced reserve instruction is received from the other directory 4-1 in the execution state of the reserve instruction received from the other and executed, the reserved state is changed to the previously reserved directory 4-0 by the forced reserve instruction from another directory. A reserve cancellation notifying means 10 for notifying that the reservation has been canceled is provided.

[0010]

According to the computer subsystem of the present invention having such a configuration, the ports of each device 6-0 to 6-n to the SCSI interface 5 are set to two ports α and β, and each device 6-0. 6-n, for example, even if the directory 4-0 is reserved, another directory 4
When the forced reserve instruction is executed from -1, it is possible to notify the previously reserved directory 4-0 that the reserved state has been released by the forced reserve instruction from another directory.

Therefore, channel 2-0, directory 4
-0 and device 6-0 are in channel 2-0 during path connection
Is down, CPU1 is down channel 2-0
Are disabled and the normal remaining channels 2-1 to 2-3 can be used to access the subsystem. Further, even if the directory 4-0 goes down while the channel 2-0, the directory 4-0 and the device 6-0 are in the path connection, the CPU 1
Prohibits access using the downed channel 2-0, and the channels 2-2 and 2 on the normal directory 4-1 side are
-3 can be used to access the subsystem.

Further, from channel 2-0 to directory 4
Even if the channel 2-0 goes down after the device 6-0 is reserved through −0 and before the path is connected, the CPU 1 disables the downed channel 2-0 and sets the normal remaining channels 2-1 to 2-1. Subsystems can be accessed using 2-3.

[0013]

2 is a block diagram of an embodiment showing the first embodiment of the present invention. In FIG. 2, 1 is a CPU of the computer, and the CPU 1 is provided with four channels 2-0 to 2-3 indicated by CH0 to CH3. Channels 2-0-2
-3, a directory 4 operating as a device control unit of the subsystem via the BMC interface 3.
-0 and 4-1 are connected.

That is, the ports A and B of the directory 4-0 are connected to the channels 2-0 and 2-1 and the ports A and B of the directory 4-1 are connected to the channels 2-2 and 2-3. Connected. For the directories 4-0 and 4-1, five devices 6-0 to 6-0 are provided in this embodiment.
6-4 known as device interface SCS
It is connected through the I interface 5.

Here, the devices 6-0 to 6-4 are SCSs.
Two ports α and β are provided as ports for the I interface 5. The directory 4-0 is SCS for one port α of the devices 6-0 to 6-4.
It connects by the I interface 5. In addition, for the ports β of the devices 6-0 to 6-4, the directory 4-
1 is connected by the SCSI interface 5.

As described above, in the present invention, the device 6
The ports for the SCSI interface 5 of -0 to 6-4 are duplicated. Furthermore, channels 2-0 to 2-3
From BM to device 6-0 to 6-4
In addition to the reserve function for saving the device, the C interface 3 and the SCSI interface 5 are also provided with the forced reserve function that can forcibly cancel the reserve and occupy it even during the reserve. .

Corresponding to the forced reserve function of this system, each of the devices 6-0 to 6-4 is provided with reserve cancellation notifying means as shown in the principle explanatory diagram of FIG. For example, taking the reservation cancellation notifying means of the device 6-0 as an example, when the reserve instruction received from the directory 4-0 is in the execution state, that is, when the forced reserve instruction is executed from the other directory 4-1 during the reserve operation. That is, when the reservation by the directory 4-0 up to that time is canceled and the reservation from the newly designated directory 4-1 is accepted, the reserve instruction is canceled by the forced reserve instruction from another directory 4-1. Is notified to the directory 4-0.

Next, in the embodiment of FIG. 2, the avoidance operation when a failure occurs in a specific device during path connection from the channel to the device or during reserve before the path connection and the apparatus goes down will be described. [Case 1] When the channel 2-0 goes down while the channel 2-0, the directory 4-0, and the device 6-0 are in the path connection; when the channel 2-0 goes down during such a path connection, the channel 2- 0, the directory 4-0 and the device 6-0 remain connected, and the device 6-
The bus of the SCSI interface 5 of the port 0 of 0 is in the bus busy state, but the port β can be used.

Therefore, the CPU 1 detects that the paths of the channel 2-0, the directory 4-0 and the device 6-0 are down, and the channel 2-2 on the directory 4-1 side.
Alternatively, one of 2-3 is used to instruct the port β of the device 6-0 to perform the forced reserve. Here, even if the CPU 1 tries to reserve the device 6-0 by using the channel 2-1, the directory 4-0 of the path causing the failure is in use and the control unit busy is responded, so the CPU 1 uses the channel. It can be determined that 2-1 cannot be used, so channel 2-2 or 2-3 will be used.

The device 6-0, which has received the forced reserve instruction from the CPU 1 for the port β of the device 6-0 from the channel 2-2 or 2-3 via the directory 4-1, receives the forced reserve instruction. Is executed to cancel the reservation up to that point, and at the same time, it is reported to the directory 4-0 that a forced reserve instruction from another directory 4-1 has been executed, and the connection with the directory 4-0 is disconnected.

When the directory 4-0 receives the execution report of the forced reserve instruction, the device 6-is issued to the channel 2-0 by the forced reserve instruction from the other directory 4-1.
Report that the connection with 0 has been released, and channel 2-0
Disconnect from. At this time, since channel 2-0 is down due to a failure, it may not give a response to the report of disconnection due to forced reserve from directory 4-0. Disconnect as an error of 0.

As a result, the channel 2 over the fault
0, the directory 4-0 and the device 6-0 are all disconnected, and thereafter the CPU 1 disables the downed channel 2-0 and the remaining normal channels 2--0.
Subsystems will be used using 1-2. [Case 2] When the directory 4-0 goes down while the channel 2-0, the directory 4-0 and the device 6-0 are in the path connection;
Since -0 can operate normally, the abnormality of the down directory 4-0 is detected and the reset instruction is given to the directory 4-0. However, since the directory 4-0 is down, even if the reset instruction is received, the device 6
The connection with the port α of −0 cannot be released, and the bus of the SCSI interface 5 for the port α remains in the bus busy state.

The access to the directory 4-0 is S
The control busy due to the bus busy of the CSI interface 5 is responded. However, since the SCSI interface bus of the port 6 of the device 6-0 can be used, the CPU 1 makes a forced reserve for the port β of the device 6-0 via the channel 2-2 or 2-3 and the directory 4-1. Give instructions.

The device 6-0 releases the reserve by the directory 4-0 by the forced reserve instruction of the port β, reports that the forced reserve has been executed from the port α to the directory 4-0, and disconnects the connection of the port α. .
Since the directory 4-0 is down, there may be no response to the forced reserve execution report from the port α of the device 6-0. In this case, the device 6-0
-0 disconnects the connection of the port α as an abnormality of the directory 4-0.

After that, the CPU 1 executes the normal directory 4-
Subsystem is used via channel 2-2 or 2-3 on the one side. Further, the CPU 1 sends the device 6-0 to the channel 2-0 from the down directory 4-0.
Detects that there is no report that the forced reserve instruction has been executed from another directory 4-1.
When it is judged that it is down to -0, the subsystem access via the directory 4-0 is prohibited, and the same failure is prevented from occurring. [Case 3] When the channel 2-0 reserves the device 6-0 through the directory 4-0 and then the channel 2-0 goes down before the path is connected; the CPU 1 brings down the channel 2-0. If the channel 2-1 is being used by another I / O device at this time,
Device 6-0 using channel 2-2 or 2-3
To force a reserve.

The device 6-0 receives the forced reserve instruction from the CPU 1 and the directory 4-located on the down side.
The reservation of 0 is canceled and the directory 4-1 is reserved. Therefore, the CPU 1 has the directory 4-
The device 6-0 can be accessed via 1. Further, when the device 6-0 executes the forced reserve instruction, the device 6-0 sends the other directory 4-1 to the directory 4-0.
It reports that the reserve state was released by the forced reserve instruction from. Directory 4-0 is device 6-0
Channel 2 receives the report of the forced reserve execution result from
The execution report of the forced reserve instruction from the other directory 4-1 is sent to -0, and the command can be accepted from the channels 2-0 and 2-1.

At this time, it may be possible that the forced reservation execution report from the directory 4-1 cannot be responded due to the channel 2-0 going down. In this case, the directory 4-0 is the device 6-for the channel 2-0. 0
With the interrupt pending by the circuit board of No. 2, the commands can be accepted from the channels 2-0 to the devices 6-1 to 6-4 other than the device 6-0 and the channels 2-1.

After that, the CPU 1 uses the down channel 2-
It is possible to use 0 to prohibit the use of the normal channels 2-1 to 2-3 to access the subsystem, and it is possible to minimize a decrease in throughput due to a failure of the channel 2-0. FIG. 3 is a flow chart showing a response process in the devices 6-0 to 6-4 when a forced reserve instruction is received during the path connection to the device from the channel of FIG.

In FIG. 3, when a forced reserve instruction is issued to the port β while the port α of the device is connected, it is determined whether or not the port β is selected in step S1, and step S1 is selected.
In step 2, the start acceptance process is executed, and when the process order comes around, it is checked in step S3 whether there is a forced reserve instruction,
If the instruction is a forced reserve instruction, the reserve process for the port β is executed in step S4, and the port α is executed in step S5.
To the directory to report execution of the forced reserve instruction by another directory received from port β.

Then, in step S6, the response from the directory to the port α is checked, and if there is a response, the process proceeds to step S8 to disconnect the port α. If there is no response, the process proceeds to step S7 and the directory down processing is performed, and similarly, the port α disconnection processing is performed in step S8. On the other hand, if the forced reserve instruction is not issued in step S3, it is reported as device busy in step S10. Furthermore, when the command is completed in step S9, the port α is disconnected in step S8.

FIG. 4 is a flow chart showing the processing operation of the directory which has received the forced reserve execution report from the device side according to the processing of FIG. In FIG. 4, when the execution report of the forced reserve instruction from the other directory is received in step S1, the disconnection process of the port α which was performing the path connection by the device reserve is executed in step S2, and the channel is disconnected in step S3. Notify that there has been a forced reserve execution report by another directory.

Subsequently, in step S4, a response from the channel is waited for, and in step S5, the bus connection with the channel is disconnected. If there is no response, in step S5, the interrupt to the channel at the device model number is held and the process proceeds to step S6 to perform the bus disconnection processing from the channel. Of course, if it is determined in step S7 that the command has ended, a bus disconnection process from the channel is performed in step S6.

FIG. 5 is a flow chart showing the device response process when the forced reserve instruction is received from the port β before the path connection after the reserve of the port α. In FIG. 5, when it is determined in step S1 that the port β is activated, the activation acceptance process is performed in step S2, and when it is determined in step S3 that the port α is reserved, step S3 is performed.
Proceed to step 4 to check if there is a forced reserve instruction. If it is a compulsory reserve instruction, the reserve release of port α and the reserve process of port β are executed in step S5, and the interrupt to the directory of port α is issued in step S6.

Subsequently, in step S7, a response from the directory to the port α is waited, and if a response is obtained, step S7 is executed.
It reports that it was executed by receiving the forced reserve instruction from the port β from another directory at 8. If there is no response to the interrupt in step S7, it is assumed that the interrupt for the directory of port α is suspended in step S9.

If the port α is not reserved in step S3, the command according to the forced reserve instruction received from the port β is executed in step S10. If the forced reserve instruction is not issued in step S4, a device busy report is issued in step S11. FIG. 6 is a flow chart showing the processing operation of the directory for the forced reserve execution report from the device side of FIG.

In FIG. 6, when an interrupt from the device is discriminated in step S1, a start acceptance process is performed in step S2, and it is discriminated in step S3 whether or not it is an execution report by a forced reserve instruction from another directory. If it is a reserve execution report, reserve release processing for the device is performed in step S4. Then, in step S5, an interrupt is issued to the channel that reserves the device, and in step S6, a response from the channel is waited for, and in step S7, an execution report based on a forced reserve instruction from another directory is issued. If no channel response is obtained in step S6, the interrupt factor for the channel is maintained.

If the report is not a forced reserve execution report in step S3, an interrupt is received in step S9 and a process for the interrupt is executed. FIG. 7 is a block diagram of an embodiment showing the second embodiment of the present invention. In this second embodiment, two ports are provided for the SCSI interface 5 of the directories 4-0 and 4-1. Characterize.

That is, two ports a and b are provided for the directory 4-0, and the port a is the device 6-0 to 6-6.
-4 to port α and port b to port β. Similarly, for the directory 4-1, two ports c and d are provided, and the ports α and 6 of the devices 6-0 to 6-4 are
Connect to each of β. Thus the directory 4-
Since 0, 4-1 has two ports for the SCSI interface 5, one directory is a device 6-
Each of the two ports α and β provided in 0 to 6-4 can be accessed.

Therefore, for example, when the directory 4-0 wants to access the device 6-0 and another directory 4-1 is connected to the device 6-1 by using the port α, the device 6-0 is connected to the device 6-0. Although the port α becomes bus busy, the directory 4-0 can access the device 6-0 by using the port β, so that the number of control unit busy reports due to bus busy in the SCSI interface 5 can be reduced.

FIG. 8 is a block diagram of an embodiment showing the third embodiment of the present invention. As with the embodiment of FIG.
Two ports are provided for the SCSI interface 5 of 0,4-1, and five devices 6-0 to 6-4 are set as one group, and in this embodiment, group A and group B, and the number of devices under the subsystem is set. It is characterized in that it can be increased.

That is, the devices 6-0 to 6- of the group A
As for the directory 4, the directory 4-
Ports α and β are connected to the port a of 0 and the port c of the directory 4-1 respectively. On the other hand, for the devices 6-0 to 6-4 of the B group, the devices under the subsystem can be doubled by connecting to the port d of the directory 4-1 by the port β, for example.

In this case, the port b of the directory 4-0
Is empty, it may be connected to the port α of the devices 6-0 to 6-4 of the B group as shown by the broken line.
Also, the port b of the directory 4-0 may be reserved for the expansion of the third C group.

[0043]

As described above, according to the present invention, by duplicating the device side with respect to the directory in the subsystem, a forced reserve instruction is issued for a failure occurring during path connection or before path connection after reservation. The function to report the execution result can limit the failure location and avoid the failure location, and minimize the subsystem down and throughput decrease due to the failure occurrence.

Further, by having two ports on the device side, it is possible to reduce the occurrence rate of control unit busy and improve the throughput. Furthermore, by duplicating the device ports, the number of devices placed under the subsystem can be increased.

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of the present invention.

FIG. 2 is a configuration diagram of an embodiment showing the first embodiment of the present invention.

FIG. 3 is a flowchart showing device response processing when a forced reserve instruction is received during a path connection from a channel to a device.

FIG. 4 is a flowchart showing directory response processing when a forced reserve execution report by another directory is received from a debiasing during reserve while a path is being connected from a channel to a device.

FIG. 5 is a flowchart showing device response processing when a forced reserve instruction is received before the path connection after reserve.

FIG. 6 is a flowchart showing directory response processing when a forced reserve execution report by another directory is received from debias before the path connection after reserve.

FIG. 7 is a block diagram of an embodiment showing a second embodiment of the present invention.

FIG. 8 is a configuration diagram of an embodiment showing a third embodiment of the present invention.

FIG. 9 is an explanatory diagram of a conventional computer subsystem.

[Explanation of symbols]

1: CPU 2-0 to 2-3: Channel (CH) 3: Channel interface (BMC interface) 4-0, 4-1: Device control unit (directory; DI
R) 5: Device interface (SCSI interface) 6-0 to 6-n, 6-10 to 6-14: Device 10: Reserve cancellation notification means

Claims (1)

[Claims] 1. A plurality of channels (2) provided in a CPU (1).
-0 to 2-3), two device control units (4-0, 4-1) are connected via the channel interface (3), and the device control units (4-0, 4-1) A plurality of devices (6) via each device interface (5)
-0 to 6-n) connected to each other, at least two devices are connected to each of the devices (6-0 to 6-n).
Two ports (α, β) are provided, and the two device control units (4-0, 4-1) are individually connected to each of the ports (α, β) via a device interface (5). In each of the devices (6-0 to 6-n), in the execution state of the reserve instruction received from the one directory (4-0), the forced reserve instruction is received from the other directory (4-1) and executed. Occasionally, a reserve cancellation notifying means (10) is provided to notify the previously reserved directory (4-0) that the reserved state has been canceled by a forced reservation instruction from another directory. Computer subsystem.